A146124 Number of n X n arrays of squares of integers summing to 5 with every element equal to at least one neighbor.

0, 32, 516, 2307, 6472, 14379, 27684, 48331, 78552, 120867, 178084, 253299, 349896, 471547, 622212, 806139, 1027864, 1292211, 1604292, 1969507, 2393544, 2882379, 3442276, 4079787

Offset

2,2

Links

Table of n, a(n) for n=2..25.

Formula

Empirical (for n>=4): a(n) = 12*n^4 - 36*n^3 - 85*n^2 + 324*n - 188. - Vaclav Kotesovec, Nov 30 2012

Conjectures from Colin Barker, Mar 23 2018: (Start)

G.f.: x^3*(32 + 356*x + 47*x^2 - 223*x^3 + 89*x^4 - 13*x^5) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>8.

(End)

Crossrefs

Sequence in context: A109384 A248070 A366551 * A125489 A084486 A161640

Adjacent sequences: A146121 A146122 A146123 * A146125 A146126 A146127

Keyword

nonn

Author

R. H. Hardin, Apr 14 2009

Status

approved